source: trunk/MagicSoft/slalib/dafin.c@ 9022

Last change on this file since 9022 was 731, checked in by tbretz, 25 years ago
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1#include "slalib.h"
2#include "slamac.h"
3void slaDafin ( char *string, int *iptr, double *a, int *j )
4/*
5** - - - - - - - - -
6** s l a D a f i n
7** - - - - - - - - -
8**
9** Sexagesimal character string to angle.
10**
11** (double precision)
12**
13** Given:
14** string char* string containing deg, arcmin, arcsec fields
15** iptr int where to start decode at (1st = 1)
16**
17** Returned:
18** iptr int advanced past the decoded angle
19** a double angle in radians
20** j int status: 0 = OK
21** +1 = default, A unchanged
22** -1 = bad degrees )
23** -2 = bad arcminutes ) (note 3)
24** -3 = bad arcseconds )
25**
26** Example:
27**
28** argument before after
29**
30** string '-57 17 44.806 12 34 56.7' unchanged
31** iptr 1 16 (points to 12...)
32**
33** a ? -1.00000
34** j ? 0
35**
36** A further call to slaDafin, without adjustment of iptr, will
37** decode the second angle, 12deg 34min 56.7sec.
38**
39** Notes:
40**
41** 1) The first three "fields" in string are degrees, arcminutes,
42** arcseconds, separated by spaces or commas. The degrees field
43** may be signed, but not the others. The decoding is carried
44** out by the dfltin routine and is free-format.
45**
46** 2) Successive fields may be absent, defaulting to zero. For
47** zero status, the only combinations allowed are degrees alone,
48** degrees and arcminutes, and all three fields present. If all
49** three fields are omitted, a status of +1 is returned and a is
50** unchanged. In all other cases a is changed.
51**
52** 3) Range checking:
53** The degrees field is not range checked. However, it is
54** expected to be integral unless the other two fields are absent.
55** The arcminutes field is expected to be 0-59, and integral if
56** the arcseconds field is present. If the arcseconds field
57** is absent, the arcminutes is expected to be 0-59.9999...
58** The arcseconds field is expected to be 0-59.9999...
59**
60** 4) Decoding continues even when a check has failed. Under these
61** circumstances the field takes the supplied value, defaulting
62** to zero, and the result a is computed and returned.
63**
64** 5) Further fields after the three expected ones are not treated
65** as an error. The pointer iptr is left in the correct state
66** for further decoding with the present routine or with slaDfltin
67** etc. See the example, above.
68**
69** 6) If string contains hours, minutes, seconds instead of degrees
70** etc, or if the required units are turns (or days) instead of
71** radians, the result a should be multiplied as follows:
72** for to obtain multiply
73** string a in a by
74** d ' " radians 1 = 1.0
75** d ' " turns 1/2pi = 0.1591549430918953358
76** h m s radians 15 = 15.0
77** h m s days 15/2pi = 2.3873241463784300365
78**
79** Called: slaDfltin
80**
81** Defined in slamac.h: DAS2R
82**
83** Last revision: 1 August 1996
84**
85** Copyright P.T.Wallace. All rights reserved.
86*/
87{
88/* Local variables */
89 int jd, jf, jm, js;
90 double arcsec, arcmin, deg;
91
92/* Preset the status to OK */
93 jf = 0;
94
95/* Defaults */
96 deg = 0.0;
97 arcmin = 0.0;
98 arcsec = 0.0;
99
100/* Decode degrees, arcminutes, arcseconds */
101 slaDfltin ( string, iptr, &deg, &jd );
102 if ( jd > 1 ) {
103 jf = -1;
104 } else {
105 slaDfltin ( string, iptr, &arcmin, &jm );
106 if ( jm < 0 || jm > 1 ) {
107 jf = -2;
108 } else {
109 slaDfltin ( string, iptr, &arcsec, &js );
110 if ( js < 0 || js > 1 ) {
111 jf = -3;
112
113 /* See if the combination of fields is credible */
114 } else if ( jd > 0 ) {
115
116 /* No degrees: arcmin, arcsec ought also to be absent */
117 if ( jm == 0 ) {
118
119 /* Suspect arcmin */
120 jf = -2;
121 } else if ( js == 0 ) {
122
123 /* Suspect arcsec */
124 jf = -3;
125 } else {
126
127 /* All three fields absent */
128 jf = 1;
129 }
130
131 /* Degrees present: if arcsec present so ought arcmin to be */
132 } else if ( jm != 0 && js == 0 ) {
133 jf = -3;
134
135 /* Tests for range and integrality */
136
137 /* Degrees */
138 } else if ( jm == 0 && dint ( deg ) != deg ) {
139 jf = -1;
140
141 /* Arcminutes */
142 } else if ( ( js == 0 && dint ( arcmin ) != arcmin )
143 || arcmin >= 60.0 ) {
144 jf = -2;
145
146 /* Arcseconds */
147 } else if ( arcsec >= 60.0 ) {
148 jf = -3;
149 }
150 }
151 }
152
153/* Unless all three fields absent, compute angle value */
154 if ( jf <= 0 ) {
155 *a = ( ( fabs ( deg ) * 60.0 + arcmin ) * 60.0 + arcsec ) * DAS2R;
156 if (jd < 0) {
157 *a = -(*a);
158 }
159 }
160
161/* Return the status */
162 *j = jf;
163}
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